By default, Elasticsearch binds to loopback addresses only — e.g. 127.0.0.1
and [::1]. This is sufficient to run a single development node on a server.

In fact, more than one node can be started from the same $ES_HOME
location on a single node. This can be useful for testing Elasticsearch’s
ability to form clusters, but it is not a configuration recommended for
production.

In order to form a cluster with nodes on other servers, your
node will need to bind to a non-loopback address. While there are many
network settings, usually all you need to configure is
network.host:

network.host: 192.168.1.10

The network.host setting also understands some special values such as
_local_, _site_, _global_ and modifiers like :ip4 and :ip6, details of
which can be found in Special values for network.hostedit.

As soon you provide a custom setting for network.host,
Elasticsearch assumes that you are moving from development mode to production
mode, and upgrades a number of system startup checks from warnings to
exceptions. See Development mode vs production modeedit for more information.